Control arrangement for gas fired dryer



E. L. ALUMBAUGH CONTROL ARRANGEMENT FOR GAS FIRED DRYER 5 Sheets-Sheet 1QM gay Dec. 6, 1966 Filed May 18, 1964 mm M10 Ink Is .w \wb 23k 5.

E. L. ALUMBAUGH CONTROL ARRANGEMENT FOR GAS FIRED DRYER Dec. 6, 1966 3Sheets-Sheet 2 MAI/V Filed May 18, 1964 CONTROL BOX GAS SOLENOID EXHAUSTL/M/f THfRMST/IT IWO TOR fi/enz ar ugefle l. Q/zmZZazg" Z Dec. 6, 1966E. L. ALUMBAUGH 3,290,027

CONTROL ARRANGEMENT FOR GAS FIRED DRYER Filed May 18, 1964 5Sheets-Sheet I5 wa of Eugene J. Qfzzmfiazg/g United States Patent3,290,027 CONTROL ARRANGEMENT FIRED DRYER Eugene L. Alumbaugh, Watson,111., assignor to Borg- Warner Corporation, Chicago, 111., a corporationof Illinois Filed May 18, 1964, Ser. No. 368,065 8 Claims. (Cl. 263-33)FOR GAS and subsequent closing of the door; cycling of an air fiowcontrol, or cycling of a thermostatic control. In such case, the gas-airmixture, remaining in the burner, is ignited before reaching the burnerports and flashes back into the burner venturi.

It is the principal object of the present invention to provide animproved control system for a gas burner assembly of the type describedwhich provides for a sufficient delay between the time the air movementbegins and the burner is ignited to insure purging of the burner ofunburned gas by the air flow to allow safe ignition.

Another object of the invention is to provide an electrical controlsystem of the character described in which a gas supply valve iselectrically-controlled by a time delay arrangement effective toinstantaneously close the gas supply valve upon any interruption ofpower and, after a suitable period of time sufficient to insure air flowpurging unburned gas from the burner, to open the valve.

Additional objects and advantages of the invention will become apparentfrom a consideration of the following specification taken in connectionwith the accompanying drawings, in which:

FIG. 1 is a side elevation of a laundry dryer embodying the improvedcontrol arrangement for the gas burner assembly thereof;

FIG. 2 is a vertical sectional view of the dryer, said section beingtaken on line 2-2 of FIG. 1;

FIG. 3 is a perspective view of the dryer, with the top wall removed;

FIG. 4 is a schematic illustration of the gas burner assembly andcertain controls therefor; and

FIG. 5 is a circuit diagram of the control arrangement.

Referring to FIGS. 1, 2, and 3, the dryer comprises a cabinet generallyindicated at and of box-like construction having top and bottom walls 11and 12, side walls 13 and 14, and front and rear walls 15, 16. Rotatablymounted in a conventional manner withincabinet 10 is a drum 17 having aperforated cylindrical wall 18, a front wall 19 with a circular openingin alignment with an opening in cabinet wall and closed by cabinet door20 for transferring clothing to and from the drum. The drum alsocomprises a rear wall 21, in the form of a disc, connected to a driveshaft 22 positioned at the rotational axis of the drum and journalled ina trunnion housing 23 supporting the drum for rotation on the rear wall16 of the cabinet. Positioned beneath the drum 17 is a hood and lintscreen assembly 24 supported on the rear cabinet wall 16. A fan orblower 25 is also positioned within the cabinet and adjacent theassembly 24, and is operatively connected to the drive shaft of a motor26. The shaft of the motor 26 is connected by a pulley 27 forming aportion of a suitable speed reducing arrangement for rotating the drum17 concurrently with opera- 3,290,027 Patented Dec. 6, 1966 tion ofblower 25. This arrangement includes a belt 28 connecting pulley 27 topulley 29 on an idler shaft 30 provided with a sprocket 31 connected bya roller chain 32 to a sprocket 33 fixed to the drum drive shaft 22.

A gas burner assembly is mounted in the upper portion of the cabinet andcomprises burners 34, 34 within a housing 35 extending between andconnected to the top wall 11 and a horizontal upper partition wall 36 ofthe cabinet. As shown in FIG. 2, operation of the blower 25 causesexternal air to flow through an opening in the cabinet top wall 11, anopening in housing wall 37 into the housing to be heated by the burners,the heated air passing through openings in housing wall 38 and cabinetpartition wall 36 into and around drum 17, an opening in cabinet lowerpartition wall 39 and the lint screen assembly 24, to the fan 25, andthence through an opening in cabinet rear wall 16 to the atmosphere.

The gas burner assembly illustrated in FIGS. 1 and 4, is well known andis provided, in conventional manner, with a gas supply line 40 connectedto the burners 34, 34 and also to a pilot burner 41 (FIG. 2) between theburners 34, 34. A valve 42 is operated by a solenoid 44 to control theflow of gas to the burners. The gas flows to the pilot burner 41 byconduit 45 and can be manually ignited. When solenoid 44 is energized,plunger 45 of valve 42 is raised to unblock passage 46 in the valve topermit gas to flow into nozzle 47 of each burner, through meteringorifice 48 in the tip of the nozzle, the nozzle 47 extending Within thecentral opening of the Venturi tube 49 to dispose the tip within thetube. Each burner is of conventional form and includes a mixer orVenturi tube portion 49 having its end provided with openings for theentrance of air into the tube for mixture with the gas and issuance ofthe gas-air mixture through the ports in the burners for ignition by aflame from the pilot burner 41 disposed adjacent the ports in both gasburners.

Various known safety controls are also provided and will be brieflydescribed. A high temperature limit control comprises a thermostat 50(FIG. 2) located at the top rear of the burner housing 35 and whichfunctions to open a normally closed switch S1 (FIG. 5) to deenergize thesolenoid 44 of the gas supply valve 42 to prevent gas flow to theburners in the event there is no air flow over the burners or arestriction of the air flow. An air fiow device 51 (FIG. 2) is a controloperating to open a switch S2 (FIG. 5) to deenergize the gas supplysolenoid should there be a reduction in the amount of air being drawnover the burner and through the dryer. This device (FIG. 2) is mountedon the side wall 37 of the housing 35 at the entrance of the air ductopening therein and comprises an air flow vane 52 pivoted at 53 toprotrude over the top edge of the duct so that it is in the air flowstream. The vane is connected to a mercury switch S2 controllingenergization of the gas supply solenoid. When the blower is operatingand air is pulled through the duct, the pressure of the air moves thevane to approximately 45 and moves the switch to its closed position. Anexhaust thermostat 54 is located at the rear of the dryer and is mountedto the back wall of the cabinet in the path of the air flow. Itsfunction is to deenergize the gas burner solenoid 44 by opening a switchS3 (FIG. 5) to interrupt a circuit of the solenoid in the event arestriction of air flow occurs in the exhaust system. The thermostat isset to open switch S2 at 180 F. and to close the switch at F. Thesesafety controls will now be described with reference to the wiringdiagram of FIG. 5.

Referring to FIG. 5, the dryer may be of the coin-controlled type and,for this purpose, is provided with a coinoperated switch S4. When thedamp clothes are in the dryer, the door is closed, and a coin isinserted in the coinactuated timer control, switch S4 is closed. Acircuit is provided to the motor TM of a conventional timer effective torotate a cam to maintain switch S4 closed for a predetermined period oftime of dryer operation. This circuit comprises lead L1 from one side ofa 115-volt line, switch S4, conductor Cl, winding of motor TM and leadL2 to the other side of the 115-volt line.

Upon closing of switch S4 and a door switch S5, a circuit is establishedfor energizing the drive motor 26. This circuit includes power lead L1;closed switches S4, S5; conductor C2; windings of motor 26; and powerlead L2. Energization of motor 26 causes operation of the blower 25 androtation of drum 21.

The present invention is directed to an improved control arrangement fora burner assembly, preferably but not necessarily using manufacturedgas, and providing for a sufficient delay between the time the air flowmovement begins and the burner is ignited to purge the burner assemblyof unburned gas and allow safe ignition. More particularly, it iscontemplated that this control arrangement is effective during operationof the dryer and in the event there is any interruption of power to thedrum and blower drive motor, and then immediate resumption of power,such, for example, as opening of the door switch by the operator, causedby inserting or extracting clothes from the dryer, and subsequentclosing of the switch by closing the door; opening and closing of theair flow control switch; or opening and closing of the thermostaticswitches by cycling of these switches.

In accordance with the invention, the control arrangement includes acircuit arrangement providing for energizing the winding of the solenoid44 of the gas valve 42 to raise the plunger 46 and allow gas to flow tothe burners 43, 43 for ignition of the gas-air mixture, flowing from theburners, by the pilot burner, the circuit arrangement includingelectrically-controlled means for insuring operation of the drive motor26 and thereby the blower 25 for a predetermined time period to purgethe burner assembly of gas prior to energization of the solenoid 44 forflow of gas-air mixture to the burner ports for ignition by the pilotburner flame.

For this purpose, and referring to FIG. 5, the circuit for drive motor26 having been established as. previously described, a circuit forenergizing the winding of solenoid 44 is controlled by a delay timermotor DTM having a winding energizable by a circuit including the leadL1; closed switches S1, S2, S3, S4, and S5; conductors C3, C4; closedstationary contact a and movable contact b of a switch HRS; conductorsC5 and C6; winding of motor DTM to the lead L2. Upon energization ofmotor DTM, the motor rotates its cam and its tooth moves from itsengagement with a movable spring arm of a normally closed switch CS1 topermit the arm to engage its contact a with contact b of this switch,rotation of the cam being continued for a predetermined time perioduntil its cam tooth engages movable spring arm of normally open switchCS2 to move and engage its contact a thereof with con-,

tact b of this switch.

Upon closing switch CS2, a circuit is then established for energizingthe winding of solenoid 44 of gas valve 42, this circuit including leadL1; closed switches S4, S5, S1, S3, and S2; C3; closed contacts a and bof switch CS2; conductor C7; winding 44; to lead L2. Simultaneously withthe energization of widing 44, a circuit is established to energize ahold relay coil HRC, this circuit including conductors C7 and C8; coilHRC; and lead L2. Upon the coil HRC being energized, the relay coilcauses its contact arm b to disengage contact a and engage contact c ofa switch HRS. Opening of contacts a and c of- SWitClh HRS causes thedescribed circuit of motor DTM to be interrupted, but the closing ofcontacts b and c of switches HRS immediately re-establishes a circuit tothe motor DTM through the normally closed contacts of switch CS1 whichmotor continues to rotate its cam until the cam tooth engages movablearm contact a of switch CS1 and opens normally closed contacts a and bof this switch to interrupt the circuit.

Upon the instantaneous pulse of switch CS2 by closing of its contacts bythe rotating cam, the solenoid 44 and coil HRC are simultaneouslyenergized and remain energized even when contacts a and b of switch CS2are opened by continued rotation of the cam because contacts b and c ofswitch HRS are held closed by coil HRC to provide a circuit continuingthe energizing of the solenoid and coil. Such circuit may be traced fromlead L1; switches S4, S5, S1, S2, and S3; C3; C4; closed contacts b andc of switch HRS; conductor C8 and, in parallel, solenoid Winding 44 andrelay coil HRC, to lead L2.

In the event there is an interruption of power to the drive motor 26,during operation of the dryer, by opening of any of the safety controlswitches S1, S2, S3, S4, and S5, the circuit to the drive motor will bebroken. In addition, as all of these switches are in series in each ofthe circuits for the solenoid 44 and coil HRC, as well as the delaytimer motor DTM, their energizing circuits will be instaneouslyinterrupted by opening of any of these switches. However, upon theclosing of the opened safety control switch or switches, the circuit tothe drive motor is immediately established and the drive motor becameoperative to rotate the drum and blower fan, and a previously describedcircuit is also concurrently established to energize motor DTM whichwill rotate its cam, for a predetermined timeinterval prior tomomentarily establishing the circuits to energize coil HRC and toenergize solenoid 44 to open valve 42 for flow of gas to the burners,energization of coil HRC thereafter providing the described circuits forholding the coil HRC and solenoid 44 energized.

It will be readily apparent the improved control arrangement providesfor a definite time delay in the event of interruption and immediaterestoration of power during operation of the dryer, to insure anyunburned gasair mixture, remaining in the burners, being purged from theburners by the air flow through the dryer prior to the admission of gasinto the burners from the gas supply line. Accordingly, there is nopossibility of the gas-air mixture, remaining in the burners, becomingignited be fore reaching the burner ports and flashing back into theburner Venturis when the gas supply is interrupted and immediatelyrestored. It has been determined an approximate ten-second delay betweenthe time the air flow begins and the burners are iginited allowssuflicient time to purge the burners of unburned gas and allows safeignition. The present time delay control system provides a suflicientand positive delay period and is effective to instantaneously close thegas supply valve upon any interruption of power. It may be noted thesystem utilizes the position of two switches to provide the delay anduses an electrical holding relay to directly control the switches toprovide instantaneous interruption of gas supply and subsequentresumption of the gas supply.

What is claimed is:

1. In a gas heated dryer, a rotatable drum adapted to contain articlesto be dried; means for circulating air through said drum including ablower; electric motor means for rotating said drum and operating saidblower; a gas burner for heating the circulated air; a normally closedvalve controlling the supply of gas to said burner; a solenoidenergizable to open said valve; and control circuits for said motormeans and said solenoid and including a safety switch havingthermostatic means normally closing said switch and responsive to apredetermined temperature of the heated air circulating through saiddrum to open said switch, switch means in said solenoid circuit and inseries circuit relation with said safety switch and controllingenergization of said solenoid, and electrically-controlled means fordelaying operation of said switch means to energize said solenoid for apredetermined time interval subsequent to operation of said thermostaticmeans to close said safety switch.

2. In a gas heated dryer, a rotatable drum adapted to contain articlesto be dried; means for circulating air through said drum including ablower; electric motor means for rotating said drum and operating saidblower; a gas burner for heating the circulating air; a normally closedvalve controlling the supply of gas to said burner; a solenoidenergizable to open said valve; and control circuits for said motormeans andsaid solenoid and including a safety switch having thermostaticmeans normally closing said switch and responsive to a predeterminedtemperature of the heated air circulating through said drum to open saidswitch; and switch means in said solenoid circuit and in series circuitrelation with said safety switch forcontrolling energization of saidsolenoid; and a timer operable, upon closing of said switch by said saidthermostatic means, to close said switch means to energize said solenoidafter a predetermined time interval.

3. In a gas heated dryer, a rotatable drum adapted to contain articlesto be dried; means for circulating air through said drum including ablower; electric motor means for rotating said drum and operating saidblower; a gas burner for heating the circulating air; a normally closedvalve controlling the supply of gas to said burner; a solenoidenergizable to open said valve; control circuits for said motor means,and said solenoid and including a safety switch having thermostaticmeans normally closing said switch and responsive to a predeterminedtemperature of the heated air circulating through said drum to open saidsafety switch, and normally open time delay switch means in seriescircuit relation with said safety switch and controlling energization ofsaid solenoid; and means for closing said switch means after apredetermined time interval subsequent to closing of said safety switchby said thermostatic means to energize said electric motor means.

4. In a gas heated dryer, a rotatable drum adapted to contain articlesto be dried; means for circulating air through said drum including ablower; electric motor means for rotating said drum and operating saidblower; a gas burner for heating the circulating air; a normally closedvalve controlling the supply of gas to said burner; a. solenoidenergizable to open said valve; a timer having an electric motor;control circuits for said motor means, said solenoid, and said electricmotor and including a safety switch having thermostatic means normallyclosing said switch and responsive to a predetermined temperature of theheated air circulating through said drum to open said safety switch, andnormally open switch means in series with said safety switch andcontrolling energization of said solenoid; and electrically-controlledmeans, in parallel circuit relation to said solenoid, for closing saidswitch means and energizable by said timer after a predetermined timeinterval subsequent to closing of said safety switch by saidthermostatic means to energize said electric motor means.

5. In a gas heated dryer, a rotatable drum adapted to contain articlesto be dried; means for circulating air through said drum including ablower; electric motor means for rotating said drum and operating saidblower; a gas burner for heating the circulating air; a normally closedvalve controlling the supply of gas to said burner; a solenoidenergizable to open said valve; a timer having a rotatable cam, and anelectric motor for rotating said cam; control circuit for said motormeans, said solenoid, and said electric motor and including a safetyswitch having thermostatic means normally closing said switch andresponsive to a predetermined temperature of the heated air circulatingthrough said drum to open said safety switch, and normally open switchmeans in series with said safety switch and controlling energization ofsaid solenoid; electrically-operated means for closing said switchmeans; and a switch controlling energization of saidelectrically-operated means and closable by said cam after apredetermined time interval subsequent to closing of said safety switchby said thermostatic means.

6. In a gas heated dryer, a rotatable drum adapted to contain articlesto be dried; means for circulating air through said drum including ablower; electric motor means for rotating said drum and operating saidblower; a gas burner for heating the circulating air; a normally closedvalve controlling the supply of gas to said burner; a solenoidenergizable to open said valve; a timer having a cam, and an electricmotor for rotating said cam; a first control circuit for said motormeans; a second control circuit for said timer motor; alternatelyestablishable third and fourth control circuits for said solenoid; afirst switch in each of said circuits and having thermostatic meansnormally closing said switch and operative to open said switch inresponse to a predetermined temperature of the heated air circulating insaid drum; a hold relay having a coil in parallel circuit relation toeach of said third and fourth control circuits and energizablesimultaneously with said solenoid and having a normally closed secondswitch in said second control circuit and a normally open third switchin said third control circuit; and a normally open fourth switch in saidfourth circuit and momentarily closable by and upon rotation of said camto provide said third circuit to energize said solenoid, and also toenergize said hold relay to open said second switch to thereby interruptsaid second control circuit and to close said third switch to therebyestablish said four circuit.

7. In a gas heated dryer, a rotatable drum adapted to contain articlesto 'be dried; means for circulating air through said drum including ablower; electric motor means for rotating said drum and operating saidblower; a gas burner for heating the circulating air; a normally closedvalve controlling the supply of gas to said burner; a solenoidenergizable to open said valve; a timer having a cam, and an electricmotor for rotating said cam; a first control circuit for said motormeans; alternately establishable second and third control circuits forsaid timer motor; alternately establishable fourth and fifth controlcircuits for said solenoid; a first switch in each of said circuits andhaving thermostatic rneans normally closing said switch and operative toopen said switch in response to a predetermined temperature of theheated air circulating in said drum; a hold relay having a coil inparallel circuit relation to each of said fourth and fifth controlcircuits and energizable simultaneously with said solenoid and having anormally closed second switch in said second control circuit and anormally open third switch in said third control circuit; a fourthnormally open switch in said fourth circuit and momentarily closable byand upon rotation of said cam to provide said third circuit to energizesaid solenoid and also to energize said hold relay to open said secondswitch to interrupt said second control circuit and to close said thirdswitch to establish said fourth circuit, and a normally closed fifthswitch in said third circuit to maintain energization of said timermotor upon interruption of said second control circuit and operable bysaid cam upon continued rotation thereof to interrupt said third circuitand thereby terminate energization of said timer motor.

8. In a gas heated dryer, a rotatable drum adapted to contain articlesto be dried; means for circulating air through said drum including ablower; electric motor means for rotating said drum and operating saidblower; a gas burner for heating the circulating air; a normally closedvalve controlling the supply of gas to said burner; a solenoidenergizable to open said valve; a timer having a cam, and an electricmotor for rotating said cam; a first control circuit for said motormeans; a second control circuit for said timer motor; a third controlcircuit for said solenoid; an electromagnetically-operated normally openfirst switch in said third circuit; an electromagnet energizable toclose said first switch; a normally open second switch closable toenergize said electromagnetic; switch means in each of said circuits andhaving thermo- 7 3 static means for opening and closing said switchmeans, References Cited by the Examiner in c 1 1 e 1 e and alsoestablishing said second circuit to energize said 2965367 12/1960 a -726333 timer motor to rotate said cam for a predetermined time 53,068,588 12/1962 Rlchterkesslng at 263*33 interval prior to closingsaid second switch to energize Y said electromagnet to close said firstswitch to energize FREDERICK MATTESON P'lmary Exammer said solenoid.JOHN J. CAMBY, Examiner. I

1. IN A GAS HEATED DRYER, A ROTATBALE DRUM ADAPTED TO CONTAIN ARTICLESTO BE DRIED; MEANS FOR CIRCULATING AIR THROUGH SAID DRUM INCLUDING ABLOWER; ELECTRIC MOTOR MEANS FOR ROTATING SAID DRUM AND OPERATING SAIDBLOWE; A GAS BURNER OF HEATING THE CIRCULATED AIR; A NORMALLY CLOSEDVALVE CONTROLLING THE SUPPLY OF GAS TO SAID BURNER; A SOLENOIDENERGIZABLE TO OPEN SAID VALVE; AND CONTROL CIRCUITS FOR SAID MOTORMEANS AND SAID SOLENOID AND INCLUDING A SAFETY SWITCH HAVINGTHERMOSTATIC MEANS NORMALLY CLOSING SAID SWITCH AND RESPONSIVE TO APREDETERMINED TEMPERATURE OF THE HEATED AIR CIRCULATING THROUGH SAIDDRUM TO OPEN SAID SWITCH, SWITCH MEANS IN SAID SOLENOID CIRCUIT AND INSERIES CIRCUIT RELATION WITH SAID SAFETY SWITCH AND CONTROLLINGENERGIZATION OF SAID SOLENOID, AND ELECTRICALLY-CONTROLLED MEANS FORDELAYING OPERATION OF SAID SWITCH MEANS TO ENERGIZE SAID SOLENOID FOR APREDETERMINED TIME INTERVAL SUBSEQUENT TO OPERATION OF SAID THERMOSTATICMEANS TO CLOSE AND SAFETY SWITCH.